PROJECT SUMMARY Activators of the tissue-protective erythropoietin receptor (EPOR/?c) demonstrate encouraging pre-clinical and early clinical results for the treatment of Friedreich?s Ataxia and Parkinson?s disease and hold significant potential for expansion to additional indications. In preliminary studies, a small molecule scaffold was identified that increased the binding of EPOR extracellular 25-250 193-216 domain (EPOR ) and a fluorescently-labeled peptide corresponding to EPOR . SAR optimization of this scaffold produced a small molecule library of both ?active? and ?inactive? molecules based on activation of EPOR/?c, activation of canonical signaling molecules, cytoprotection in cell-based assays and ability to increase frataxin protein in vitro and in vivo. The central goal of this Phase 1 SBIR Proposal is to establish a homogeneous, high-throughput receptor-domain interaction assay capable of identifying and ranking small molecule activators of EPOR/?c. The key objectives are to (1) evaluate fluorescence-polarization, FRET/HTRF and Alpha methodologies to demonstrate association of peptide/receptor and receptor domains in solution, (2) demonstrate increased association of peptide/receptor and receptor domains in the presence of validated small molecule activators of EPOR/?c and (3) demonstrate that the assay is capable of discriminating between validated ?active? and ?inactive? small molecules in a proprietary small molecule library. If successfully established, this assay would be used to support (1) lead-optimization of known receptor-activating scaffolds and (2) a high-throughput screen to identify new receptor activating scaffolds with follow-on optimization. The latter studies would be the subject of a future Phase II application, which would also include an assessment of small molecule binding site(s), receptor activation, cytoprotective activity and the ability of these small molecules to increase frataxin protein.